Machine preparation of milkshakes generally takes place by arranging a water-comprising basic substance in a freezing cylinder. A fraction of the basic substance positioned close to the wall of the freezing cylinder will partially freeze. The actual cooled milkshake can be obtained by scraping the frozen fraction from the wall of the freezing cylinder, grinding the frozen fraction and, subsequently, mixing the frozen fraction with the unfrozen fraction of the basic substance. The milkshake will generally also be aerated to provide the milkshake with a lighter character. Although this method is applied industrially on a large-scale in the market, this method for preparing and, in particular, cooling milkshakes has a number of drawbacks. A significant drawback of the known method is that a relatively large number of moving components, such as a scraper and breaking means for crushing the frozen fraction, are required to enable preparation of the milkshake. This makes the preparation method relatively time-consuming. Furthermore, the equipment required to apply the known preparation method, provided with the scraper and the breaking means, is relatively complex and requires relatively frequent maintenance and is, therefore, relatively expensive.
British Patent Application No. 2 408 467 discloses a fluid carbonating system comprising a carbonator tank for containing fluid and means to inject gas into fluid in the tank to create a swirling motion of the fluid within the tank, wherein the gas may be formed by CO2 gas under. However, tests have shown that the injection of a cryogenic cooling medium into the drink does not result in a satisfactory method of preparation either, since ice formation will generally occur in and around a nozzle of the then applied injection means, whereby further feed of the cryogenic cooling medium is no longer possible.